This invention relates to thermoplastic polymers which are useful in molding plastic materials for contact with body fluids. More particularly, it relates to a thermoplastic polymer composed of block radial polymers of the diene-aryl substituted olefin butadiene-styrene type which have blended with them certain polymeric materials to form a plastic composition having a high degree of clarity which are particularly useful in extruding or molding tubing, drip chambers and other components useful in the field of parenteral administration.
Recently, radial block polymers of the diene-aryl substituted olefin butadiene-styrene type have been of particular interest in that they display high tensile strength without vulcanization or filler reinforcement. These copolymers can be processed on conventional plastics or rubber equipment without the addition of plasticizers. In U.S. Pat. Nos. 3,281,383 and 3,078,254, processes for making such radial block copolymers are described. Further, particular blends of vulcanized butadiene-styrene block copolyers are indicated in U.S. Pat. No. 3,646,161. In U.S. Pat. No. 3,562,355, a mechanical blend of a butadiene-styrene copolymer is described in combination with a polyester urethane. The prior art nowhere describes a blend of nonvulcanized radial block copolymers of the butadiene-styrene type wherein the butadiene-styrene amounts are of a certain minimum quanity so that when they are combined with certain polymeric materials, they will form a plastic composition having a sufficient clarity, hardness, tensile strength and elongation to be readily adaptable for use in composing plastic materials for contact with parenteral fluids. In addition, the prior art nowhere describes a plastic composition which is readily suitable for use in the medical plastics field which will have low alkaline extraction values so that ingredients in the composition are not extracted into the fluids to be administered.
It is an advantage of the present invention to provide a novel blend of radial block copolymers of the butadiene-styrene type with other polymeric materials. Other advantages are a thermoplastic composition of the radial block copolymer type which have a high degree of clarity so that they can replace polyvinylchloride as a material in the forming of medical plastic product such as tubing, drip chambers, injection reseal device and other parenteral administration equipment, a novel radial block copolymer mixture which can be readily molded, extruded and otherwise processed by customary processes, a thermoplastic material which is compatible with the usual plasticizers, fillers, chelators, lubricants, etc. which are necessary in the fabrication of plastic materials.